Wednesday’s move appears aimed at preventing a chaotic exit from the country, as happened recently in Sudan, where U.S. citizens were spirited to a port city amid fighting in the nation’s capital, and after the fall of Kabul, where an attack during the 2021 evacuation left 13 U.S. service members dead. The State Department ordered a similar evacuation from Haiti last week amid deteriorating security there.

“The Department of State has no higher priority than the safety and security of U.S. citizens overseas, including U.S. government personnel serving abroad,” State Department spokesman Matthew Miller said in a statement. He said that the departure had been ordered because of “ongoing developments in Niger and out of an abundance of caution.”

“The United States rejects all efforts to overturn Niger’s constitutional order,” Miller said.

Key embassy leadership will remain in place in Niger, the announcement said, but the embassy has suspended routine services and will only be able to provide emergency assistance to U.S. citizens in the country. The State Department on Tuesday posted a form for U.S. citizens in Niger to fill out if they want help leaving the country.

The United States also has two military bases and about 1,000 troops inside the country, principally for counterterrorism purposes and partnered activities with Nigerien forces.

Brig. Gen. Patrick Ryder, a Pentagon spokesman, said there had been no changes to the U.S. military posture in Niger amid the State Department’s ordered departure and that the State Department had not requested assistance from military personnel or equipment in implementing its order.

“We continue to monitor this fluid and evolving situation and reiterate our focus on a diplomatic solution,” Ryder said in a statement.

The Nigerien capital of Niamey remains comparatively calm, but worries are growing that a tense situation could suddenly devolve. The Biden administration had placed hopes in President Mohamed Bazoum, who came to office in 2021 in Niger’s first democratic transition. He had been a symbol of hope for democracy in Africa’s coup-hit Sahel region, but the leader of the presidential guard led an effort to depose him last week, and he remains surrounded by gunmen in the presidential residence.

French and Italian military aircraft began an evacuation of European citizens in Niger on Tuesday, after demonstrators on Sunday attacked the French Embassy, and some U.S. citizens already departed on the flights. France, the former colonial ruler of Niger, is a target of particular ire in the country, and State Department officials did not initially feel the need to evacuate U.S. citizens in turn.

But the department had told U.S. citizens on Tuesday to “shelter in place, limit unnecessary movements, and continue to avoid transiting the downtown & Presidential Palace area. Borders and the airport remain closed and commercial flights to and from Niamey will reportedly be suspended until August 5.”

The Biden administration has been cautious about taking any steps that could entrench the presidential guard and make it harder for Bazoum to return to power. U.S. diplomats have held out hope the ouster could be reversible, and have refrained for now from calling it a “coup,” since they are cautious about the suspension of security and economic cooperation that could result from the designation. Ordering an evacuation was also seen as potentially sending a pessimistic signal.

But as the days have progressed with Bazoum still in detention, hopes of a reversal are starting to fade.

After the presidential guard detained Bazoum last week, guard head Gen. Abdourahmane Tchiani declared himself the country’s new leader. The State Department and the Pentagon have been engaged in intense efforts to convince the leaders of the Nigerien military, whose position remains unclear, to pressure the gunmen to reverse course.

The Economic Community of West African States, a regional grouping, warned that they might intervene militarily in Niger if Bazoum is not restored to power by Sunday. But Niger’s western neighbors Mali and Burkina Faso, which are led by military juntas, have backed the forces who deposed the president.

Dan Lamothe and Missy Ryan contributed to this report.